953 resultados para Research work
Resumo:
A large number of catastrophic accidents were aroused by the instability and destruction of anti-dip rock masses in the worldwide engineering projects, such as hydropower station, mine, railways and so on. Problems in relation to deformation and failure about anti-dip rock slopes are significant for engineering geology research. This dissertation takes the Longpan slope in the Jinsha River as a case to study the deformation mechanism of large-scale anti-dip rock masses and the slope stability analysis method. The primary conclusions are as follows. The Dale Reach of Jinsha River, from Longpan to the debouchment of Chongjiang tributary, is located in the southeastern margin of the Qinghai-Tibet Plateau. Longpan slope is the right embankment of Dale dam, it is only 26 km to the Shigu and 18 km to Tiger Leaping Gorge. The areal geology tectonic structures here area are complicated and blurry. Base on the information of geophysical exploration (CSAMT and seismology) and engineering geological investigation, the perdue tectonic pattern of Dale Reach is put forward for the first time in this paper. Due to the reverse slip of Longpan fault and normal left-rotation of Baihanchang fault, the old faulted valley came into being. The thick riverbed sediments have layered characters of different components and corresponding causes, which attribute to the sedimentary environments according with the new tectonic movements such as periodic mountain uplifting in middle Pleistocene. Longpan slope consists of anti-dip alternate sandstone and slate stratums, and the deformable volume is 6.5×107m3 approximately. It was taken for an ancient landslide or toppling failure in the past so that Dale dam became a vexed question. Through the latest field surveying, displacement monitoring and rock masses deforming characters analyses, the geological mechanism is actually a deep-seated gravitational bending deformation. And then the discrete element method is used to simulate the deforming evolution process, the conclusion accords very well with the geo-mechanical patterns analyses. In addition strength reduction method based on DEM is introduced to evaluate the factor of safety of anti-dip rock slope, and in accordance with the expansion way of the shear yielding zones, the progressive shear failure mechanism of large-scale anti-dip rock masses is proposed for the first time. As an embankment or a close reservoir bank to the lower dam, the stability of Longpan slope especially whether or not resulting in sliding with high velocity and activating water waves is a key question for engineering design. In fact it is difficult to decide the unified slip surface of anti-dip rock slope for traditional methods. The author takes the shear yielding zones acquired form the discrete element strength reduction calculation as the potential sliding surface and then evaluates the change of excess pore pressure and factor of stability of the slope generated by rapid drawdown of ponded water. At the same time the dynamic response of the slope under seismic loading is simulated through DEM numerical modeling, the following results are obtained. Firstly the effective effect of seismic inertia force is resulting in accumulation of shear stresses. Secondly the discontinuous structures are crucial to wave transmission. Thirdly the ultimate dynamic response of slope system takes place at the initial period of seismic loading. Lastly but essentially the effect of earthquake load to bringing on deformation and failure of rock slope is the coupling effect of shear stresses and excess pore water pressure accumulation. In view of limitations in searching the critical slip surface of rock slope of the existing domestic and international software for limit equilibrium slope stability analyses, this article proposes a new method named GA-Sarma Algorithm for rock slope stability analyses. Just as its name implies, GA-Sarma Algorithm bases on Genetic Algorithm and Sarma method. GA-Sarma Algorithm assumes the morphology of slip surface to be a broken line with traceability to extend along the discontinuous surface structures, and the slice boundaries is consistent with rock mass discontinuities such as rock layers, faults, cracks, and so on. GA-Sarma Algorithm is revolutionary method that is suitable for global optimization of the critical slip surface for rock slopes. The topics and contents including in this dissertation are closely related to the difficulties in practice, the main conclusions have been authorized by the engineering design institute. The research work is very meaningful and useful for the engineering construction of Longpan hydropower station.
Resumo:
The large ancient underground rock caverns in Longyou is an important component of grotto cultural. Current task facing the long-term preservation of these unmovable cultural relics is arduous and challenging. The deformation failure of the caverns' surrounding rock is deteriorating. The weathering velocity of these caverns is accelerating. With the strength of caverns' surrounding rock worsening, critical rocks were generated in local regions of the caverns' vault and posing a threat to the security of people passing by. Selection of a maximum-security route and construction a aisle in the caverns might be an efficient way to ensure the security of tourists and reach the target of long-term preservation. The deformation and destruction of the ancient underground caverns is primarily dominated by geological conditions and the special structure of caverns. Based on field investigation, several fundamental conditions for deformation and failure are recognized, and nine deformation and fracture patterns of the Longyou grotto are proposed. In order to judge the stability of caverns’ surrounding rock, the element safety coefficient method is presented. An explicit explanation for the meaning of the method is deduced using Mohr-Coulomb strength criterion. Numerical analyses are carried out in the dissertation through FLAC3D code. Through numerical analysis, the stress distribution regularities of the caverns’ roofs, piles and public side wall are analysed, and the stability properties of caverns’ surrounding rock are also assessed. At the same time, the element safety coefficient method is introduced to contrast the stability degree of different regions in caverns. The above analyses are bases for choosing the optimal tourism routes in the caverns of Longyou grotto. The impact of surface load on the stability of shallow buried cavities in Longyou grotto is evaluated, the results show that building load has significant influence on the stability of the No.1 cavern’s roof, pile and public side wall between the No.1 cavern and the No.2 cavern, pedestrian load has less impact on the stability of surrounding rock than building load. The principles for choosing the optimal tourism routes in the caverns are discussed. With these principles, the dissertation makes a systematic research on the geological analytic method, numerical analytic method and meeting tourism requirements method, which are used in selecting the optimal tourism routes in the caverns. In order to achieve the best effect in the process of tourism routes selection, the above three method are integrated through Theory of Engineering Geomechanics Meta-system(EGMS). According to field investigations, numerical analyses, tourism requirements and expert experiences, the optimal tourism routes through No.1 to No.5 cavern are determined preliminarily. The obtained results from the research work are useful for the security aisle's construction, they also have reference value to other projects in practice.
Resumo:
There are many Archean TTG grey suites in the Wutaishan area, northern Shanxi Province, China. In the past one hundred years, many geologists have done excellent research work in the Wutaishan and its adjacent regions. However, the TTG suites were almost neglected. Located in the northern slope of Mt. Hengshan-namely the Archean Hengshan Island Arc, intruded the Zhujiafang supercrustal rocks at almost 2.5Ga, the Yixingzhai TTG Suite is originated from partial melting of the ancient lower crust upper mantle by REE and trace elements, and the emplacement occurred in an Archean island arc. The rocks are mainly of tonalitic, I type, and calc-alkaline trends are found in the magmatic evolution. At almost 1.8 Ga, the suite was transformed to be dome-like schists in an arc-arc collision event, and the rocks were metamorphosed to an extent of amphibolitic to granulitic facies. The peak metamorphic condition is of 710-760 ℃/0.68-0.72GPa, and the subsequent cooling history is recorded as 560-620 ℃/0.46-0.60GPa. In the center of the Mt. Wutaishan-known as the Archean Wutaishan Island Arc, intruded the Archean Chechang-Beitai TTG Suite, which is of 2.5Ga old and of trondhjemitic and tonalitic, with coexisting I- and S-types and a trondhjemitic magmatic evolution trend. Through REE and trace elements, the suite is believed to be from the partial melting of the ancient lower crust or upper mantle. The 1.8 Ga collision event also made the suite gneissic and the it was metamorphosed to be amphibolitic facies, whose peak condition is approximately of 680 (±50) ℃/0.7Gpa, and the subsequent cooling process is recorded as 680 (±50) ℃、550(±50) ℃、420(±10) ℃. Crustal growth is fulfilled through magmatic intrusion as well as eruption at about 2.5Ga, arc-arc collision at about 1.8 Ga in the Wutaishan area and its environs. Additionally, the biotite-muscovite and muscovite-plagioclase geothermometers are refined, and the biotite-hornblende geothermometer is developed in this dissertation.
Resumo:
Based on brief introduction of seismic exploration and it's general developing situation, the seismic exploration method in field work implementation and some problems frequently encountered in field, which should be pay attention to, are analyzed in detail. The most economic field work techniques are emphasized. Then the seismic data processing flow and it's interpretation technique about the processing results are presented. At last four examples of seismic prospecting in gold deposits are showed. The main conclusions of our research are: 1. Seismic prospecting technique is a very efficient method in the prediction of concealed gold deposits. With appropriate application, it can absolutely reflect the detail underground geological structure in the condition of rugged area and complicated geological environment. 2. The field geometry should be designed and changed according to different kinds of objective exploration depth and ground situation. The best field implementing parameters which include offset, the distance between two adjacent traces, the quantity of dynamite and the depth of hole for explosion, should be determined with examination. Only this way, the high quality original seismic data can be gotten. 3. In seismic data processing, the edition of invalid trace and source gather, signal enhancement, velocity analysis and migration are the key steps. It has some different points with conventional processing and needs a new processing flow and methods which is suitable to the data acquired in rugged area and complicated geological environment. 4. The new common reflection area stacking method in crooked line data processing is an efficient method to improve the signal to noise ratio of seismic data The innovations of our research work are: 1. In the areas which were considered to be forbidden zone, we implement the seismic exploration in several gold deposits in China through our application. All acquire distinguished effects. This show the seismic exploration method is a new effective method in the prediction of concealed gold deposits. 2. We developed a set of seismic field work techniques and data processing which is suitable to complex environment, especially find a effective method in stacking and noise elimination in crooked line data processing. 3. In the field of seismic profile interpretation, through our research work, we are convinced of that: in different kinds of geological condition, the seismic reflection character are not same. For example the lava, the intrusion rock and sediment layers are different in the character of reflection structure and strength. So we accumulate some experience about seismic data interpretation in the area of gold deposits.
Resumo:
As an important measure to understand oil and gas accumulation during petroleum exploration and development, Petroleum geological model is an integrated system of theories and methods, which includes sedimentology, reservoir geology, structural geology, petroleum geology and other geological theories, and is used to describe or predict the distribution of oil and gas. Progressive exploration and development for oil and gas is commonly used in terrestrial sedimentary basin in China for the oil and gas generation, accumulation and exploitation are very intricate. It is necessary to establish petroleum geological model, adaptive to different periods of progressive exploration and development practice. Meanwhile there is lack of an integrated system of theories and methods of petroleum geological model suitable for different exploration and development stages for oil and gas, because the current different models are intercrossed, which emphasize their different aspects. According to the characteristics of exploration and development for the Triassic oil and gas pool in Lunnan area, Tarim Basin, the Lunnan horst belt was selected as the major study object of this paper. On the basis of the study of petroleum geological model system, the petroleum geological models for different exploration and development stages are established, which could be applied to predict the distribution of oil and gas distribution. The main results are as follows. (1) The generation-accumulation and exploration-development of hydrocarbon are taken as an integrated system during the course of time, so petroleum exploration and development are closely combined. Under the guidance of some philosophical views that the whole world could be understood, the present writer realizes that any one kind of petroleum geological models can be used to predict and guide petroleum exploration and development practice. The writer do not recognize that any one kind of petroleum geological models can be viewed as sole model for guiding the petroleum exploration and development in the world. Based on the differences of extents and details of research work during various stage of exploration and development for oil and gas, the system of classification for petroleum geological models is established, which can be regarded as theoretical basis for progressive petroleum exploration and development. (2) A petroleum geological model was established based on detailed researches on the Triassic stratigraphy, structure, sedimentology and reservoir rocks in the Lunnan area, northern Tarim Basin. Some sub-belt of hydrocarbon accumulation in the Lunnan area are divided and the predominate controlling factors for oil and gas distribution in the Lunnan area are given out. (3) Geological models for Lunnan and Jiefangqudong oil fields were rebuilt by the combinations of seismology and geology, exploration and development, dynamic and static behavior, thus finding out the distribution of potential zones for oil and gas accumulations. Meanwhile Oil and gas accumulations were considered as the important unit in progressive exploration and development, and the classification was made for Lunnan Triassic pools. Petroleum geological model was created through 3D seismic fine interpretation and detailed description of characteristics of reservoir rocks and the distribution of oil and gas, especially for LN3 and LN26 well zones. The possible distribution of Triassic oil traps and their efficiency in the Lunnan area has been forecasted, and quantitative analysis for original oil(water) saturation in oil pools was performed. (4) The concept of oil cell is proposed by the writer for the first time. It represents the relatively oil-rich zones in oil pool, which were formed by the differences of fluid flows during the middle stage of reservoir development. The classification of oil cells is also given out in this paper. After the studies of physical and numerical modeling, the dominant controlling factors for the formation of various oil cells are analyzed. Oil cells are considered as the most important hydrocarbon potential zones after first recovery, which are main object of progressive development adjustment and improvement oil recovery. An example as main target of analysis was made for various oil cells of Triassic reservoir in the LN2 well area. (5) It is important and necessary that the classification of flow unit and the establishment of geological model of flow unit based on analysis of forecast for inter-well reservoir parameters connected with the statistical analysis of reservoir character of horizontal wells. With the help of self-adaptive interpolation and stochastic simulation, the geological model of flow units was built on the basis of division and correlation of flow units, with which the residual oil distribution in TIII reservoir in the LN2 well area after water flooding can be established.
Resumo:
Scientists have paid much attention to the greenhouse effects and the greenhouse gases for the fact of global warming. There are many uncertainties in the prediction of future climatic change. One of the important reasons causing the uncertainties is insufficient researches of the sources and sinks of greenhouse gases, especially, there is a missing sink in the global carbon cycle. The recent researches proposal that there may be an important carbon sink in the middle-latitude terrestrial ecosystems (vegetation and soil) in the North Hemisphere, despite that there is much disputation about its position and amplitude. Chinese loess is located in the middle latitude area in the North Hemisphere, what kind of role does it play in and how does it influence on the balance of the global greenhouse gases budget? For this reason, many samples were taken and analyzed from wide range and multi-stratum of Chinese loess to understand characteristics of major greenhouse gases in loess and loess possible effect on global greenhouse gas budget. Using self-made spiral corer, we totally took 81 gas samples and 65 soil samples from 7 loess profiles in China such as Zhaitang loess section of Beijing, Pianguan, Xingxian, Lishi, Puxian, Jishan loess section of Shanxi Province, and Luochuan loess section of Shaanxi Province. The gas concentrations for CO_2, CH_4 and N_2O, the contents of N_2, O_2 and carbonate, and the carbon isotopic compositions of CO_2 and carbonate in loess strata sequences are observed and measured. In addition, 19 gas samples data of the Weinan loess section, Shaanxi Province are combination with this research to study characteristics of greenhouse gases in loess. This research indicates that (1) the free gases in loess are neither paleo-atmospheric gases nor modern atmospheric gases; (2) the concentrations of CO_2, CH_4 and N_2O in loess are higher than atmospheric level; (3) the δ~(13)C of loess CO_2 shows that the CO_2 in loess mainly comes from the oxygenolysis of organic matters, but because of isotopic exchange with carbonate in loess, the carbon isotopic exchange with carbonate in loess, the carbon isotopic compositions of loess CO_2 are much more heavier than organic original CO_2; (4) the concentration of CH_4 in Malan loess is lower because it is not favorable for the decomposition of anaerobic bacteria in the Malan Loess; (5) estimation of the total amount of the carbonate in loess reveals that loess is a huge carbon reservoir (about 850PgC). In addition, the impact of the deuterogenic carbonatization during the loess accumulation on the global carbon cycle was discussed, and the preliminary conclusion is that the research work is still not enough to evaluate the effect of loess on the sources and sinks of the anthropogenic CO_2.
Resumo:
During the exploration of fractured reservoirs, worldwide difficult problems will be encountered: how to locate the fractured zones, how to quantitatively determine the azimuth, density, and distribution of the fractures, and how to compute the permeability and porosity of the fractures. In an endeavor to solve these problems, the fractured shale reservoir in SiKou area of ShengLi oil field was chosen as a study area. A study of seismic predictive theory and methods for solving problems encountered in fractured reservoir exploration are examined herein. Building on widely used current fractured reservoir exploration techniques, new seismic theories and methods focusing on wave propagation principles in anisotropic medium are proposed. Additionally, integrated new seismic data acquisition and processing methods are proposed. Based on research and application of RVA and WA methods from earlier research, a new method of acoustic impedance varying with azimuth (IPVA) creatively is put forth. Lastly combining drilling data, well log data, and geologic data, an integrated seismic predictive method for cracked reservoir bed was formed. A summary of the six parts of research work of this paper is outlined below. In part one, conventional geologic and geophysical prediction methods etc. for cracked reservoir exploration are examined, and the weaknesses of these approaches discussed. In part two, seismic wave propagation principles in cracked reservoirs are studied. The wave equation of seismic velocity and attenuation factor in three kinds of fracture mediums is induced, and the azimuth anisotropy of velocity and attenuation in fracture mediums is determined. In part three, building on the research and application of AVA and WA methods by a former researcher, a new method of acoustic impedance creatively varying with azimuth (IPVA) is introduced. A practical software package utilizing this technique is also introduced. In part four, Base on previously discussed theory, first a large full azimuth 3d seismic data (70km~2) was designed and acquired. Next, the volume was processed with conventional processing sequence. Then AVA, WA, and IPVA processing was applied, and finally the azimuth and density of the fractures were quantitatively determined by an integrated method. Predictions were supported by well data that indicate the approach is highly reliable. in part five, geological conditions contributing to cracked reservoir bed formation are analyzed in the LuoJia area resulting in the discovery that the main fractured zones are related to fault distribution in the basin, that also control the accumulation of the oil and gas, the generation mechanisms and types of fractured shale reservoirs are studied. Lastly, by using full 3D seismic attributes, azimuth and density of cracked reservoir zones are successfully quantitative predicted. Using an integrated approach that incorporates seismic, geologic and well log data, the best two fractured oil prospects in LouJia area are proposed. These results herein represent a break through in seismic technology, integrated seismic predictive theory, and production technology for fractured reservoirs. The approach fills a void that can be applied both inside China, and internationally. Importantly, this technique opens a new exploration play in the ShengLi oil field that while difficult has substantial potential. Properly applied, this approach could play an important role toward stabilizing the oil field' production. In addition, this technique could be extended fracture exploration in other oil fields producing substantial economic reward.
Resumo:
Halfgraben-like depressions have multiple layers of subtle traps, multiple coverings of oil-bearing series and multiple types of reservoirs. But these reservoirs have features of strong concealment and are difficult to explore. For this reason, many scholars contribute efforts to study the pool-forming mechanism for this kind of basins, and establish the basis for reservoir exploration and development. However, further study is needed. This paper takes HuiMin depression as an example to study the pool-forming model for the gentle slope belts of fault-depression lake basins. Applying multi-discipline theory, methods and technologies including sedimentary geology, structural geology, log geology, seismic geology, rock mechanics and fluid mechanics, and furthermore applying the dynamo-static data of oil reservoir and computer means in maximum limitation, this paper, qualitatively and quantitatively studies the depositional system, structural framework, structural evolution, structural lithofacies and tectonic stress field, as well as fluid potential field, sealing and opening properties of controlling-oil faults and reservoir prediction, finally presents a pool-forming model, and develops a series of methods and technologies suited to the reservoir prediction of the gentle slope belt. The results obtained in this paper richen the pool-forming theory of a complex oil-gas accumulative area in the gentle slope belt of a continental fault-depression basin. The research work begins with the study of geometric shape of fracture system, then the structural form, activity stages and time-space juxtaposition of faults with different level and different quality are investigated. On the basis of study of the burial history, subsidence history and structural evolution history, this paper synthesizes the studied results of deposition system, analyses the structural lithofacies of the gentle slope belt in the HuiMing Depression and its controlling roles to oil reservoir in the different structural lithofacies belts in time-space, and presents their evolution patterns. The study of structural stress field and fluid potential field indicates that the stress field has a great change from the Dong Ying stages to nowadays. One marked point among them is that the Dong Ying double peak- shaped nose structures usually were the favorable directional area for oil and gas migration, while the QuDi horst became favorable directional area since the GuanTao stage. Based on the active regular of fractures and the information of crude oil saturation pressure, this paper firstly demonstrates that the pool-forming stages of the LingNan field were prior to the stages of the QuDi field, whici provides new eyereach and thinking for hydrocarbon exploration in the gentle slope belt. The BeiQiao-RenFeng buried hill belt is a high value area with the maximum stress values from beginning to end, thus it is a favorable directional area for oil and gas migration. The opening and sealing properties of fractures are studied. The results obtained demonstrate their difference in the hydrocarbon pool formation. The seal abilities relate not only with the quality, direction and scale of normal stress, with the interface between the rocks of two sides of a fault and with the shale smear factor (SSF), but they relate also with the juxtaposition of fault motion stage and hydrocarbon migration. In the HuiMin gentle slope belt, the fault seal has difference both in different stages, and in different location and depth in the same stage. The seal extent also displays much difference. Therefore, the fault seal has time-space difference. On the basis of study of fault seal history, together with the obtained achievement of structural stress field and fluid potential field, it is discovered that for the pool-forming process of oil and gas in the studied area the fault seal of nowadays is better than that of the Ed and Ng stages, it plays an important role to determine the oil column height and hydrocarbon preservation. However, the fault seal of the Ed and Ng stages has an important influence for the distribution state of oil and gas. Because the influential parameters are complicated and undefined, we adopt SSF in the research work. It well reflects synthetic effect of each parameter which influences fault seal. On the basis of the above studies, three systems of hydrocarbon migration and accumulation, as well as a pool-forming model are established for the gentle slope belt of the HuiMin depression, which can be applied for the prediction of regular patterns of oil-gas migration. Under guidance of the pool-forming geological model for the HuiMin slope belt, and taking seismic facies technology, log constraint evolution technology, pattern recognition of multiple parameter reservoir and discrimination technology of oil-bearing ability, this paper develops a set of methods and technologies suited to oil reservoir prediction of the gentle slope belt. Good economic benefit has been obtained.
Resumo:
Nansha Islands as sacred territory of China, containing abundant natural resources is the important area of sustaining development of Chinese people. Safeguarding and developing Nansha Islands has become one important part to develop ocean resource of China in 21 century. Engineering geological problems will be faced inevitably in the processes of engineering construction. Coral reef is a new kind of soil and rock and has special engineering characteristics. This doctoral dissertation researches deeply and systematically the regional engineering geology environmental properties and quality, engineering geological characteristics of coral reefs sand on the basis of synthetic analysis of hydrology, climate, geology, geomorphology and engineering field exploration information and combining the experimental data. 1. Put forward the division program of engineering geological environment of Nansha Islands according to the data of hydrology, geology and sediments, and also deeply study the properties of each division. Evaluate the quality of engineering geological environment by fuzzy mathematics and draw the evaluation map of quality of engineering geological environment. The research work provides background support of engineering geological environment to program of resource development in Nansha Islands. 2. Structures of coral reefs have been analyzed. The model of engineering geological zone has been proposed on the basis of geomorphologic zone and combining the strata and ocean dynamic environment. The engineering construction appropriation of each zone is praised. 3. The physical and mechanical properties of coral sands are researched. The results show that coral sands have high void ratio, non-regular shape, easy grain crushing and large compressibility. Shear-expansion takes place only at very low confining pressure and shear-contraction of volumetric strain occurs at higher confining pressure. Internal friction angle decreases with the increasing of confining pressure. The grain crushing property is the main factor influencing the mechanical characteristics. 4. A revised E-ν constitutive model is proposed which considers the change of internal friction angle with confining pressure, and parameter values are also determined. 5. The stability of Yongshu Reef by is analysed for the purpose of serving engineering struction. The process and mechanism of deformation and failure of foundation and slope is analyzed by finite-element method.
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This dissertation that includes most of the P. PH.D research work during 2001~2002 covers the large-scale distribution of continental earthquakes in mainland China, the mechanism and statistic features of grouped strong earthquakes related to the tidal triggering, some results in earthquake prediction with correlativity analysis methods, and the flushes from the two strong continental earthquakes in South Asia in 2001. Mainland China is the only continental sub-plate that is compressed by collision boundaries at its two sides, within which earthquakes are dispersive and distributed as seismic belts with different widths. The control capability of the continental block boundaries on the strong earthquakes and seismic hazards is calculated and analyzed in this dissertation. By mapping the distribution of the 31282 ML:3s2,0 earthquakes, I found that the depth of continental earthquakes depend on the tectonic zonings. The events on the boundaries of relatively integrated blocks are deep and those on the new-developed ruptures are shallow. The average depth of earthquakes in the West of China is about 5km deeper than that in the east. The western and southwestern brim of Tarim Basin generated the deepest earthquakes in mainland China. The statistic results from correlation between the grouped M7 earthquakes and the tidal stress show that the strong events were modulated by tidal stress in active periods. Taking Taiwan area as an example, the dependence of moderate events on the moon phase angles (£>) is analyzed, which shows that the number of the earthquakes in Taiwan when D is 50° ,50° +90° and 50° +180° is more than 2 times of standard deviation over the average frequency at each degree, corresponding to the 4th, 12th and 19th solar day after the new moon. The probability of earthquake attack to the densely populated Taiwan island on the 4th solar day is about 4 times of that on other solar days. On the practice of earthquake prediction, I calculated and analyzed the temporal correlation of the earthquakes in Xinjinag area, Qinghai-Tibet area, west Yunnan area, North China area and those in their adjacent areas, and predicted at the end of 2000 that it would be a special time interval from 2001 to 2003, within which moderate to strong earthquakes would be more active in the west of China. What happened in 2001 partly validated the prediction. Within 10 months, there were 2 great continental earthquakes in south Asia, i.e., the M7.8 event in India on Jan 26 and M8.1 event in China on Nov. 14, 2001, which are the largest earthquake in the past 50 years both for India and China. No records for two great earthquakes in Asia within so short time interval. We should speculate the following aspects from the two incidences: The influence of the fallacious deployment of seismic stations on the fine location and focal mechanism determination of strong earthquakes must be affronted. It is very important to introduce comparative seismology research to seismic hazard analysis and earthquake prediction research. The improvement or changes in real-time prediction of strong earthquakes with precursors is urged. Methods need to be refreshed to protect environment and historical relics in earthquake-prone areas.
Resumo:
How to create a new method to solve the problem or reduce the influence of that the result of the seismic waves scattering nonlinear inversion is not uniqueness is a main purpose of this research work in the paper. On the background of research into the seismic inversion, new progress of the nonlinear inversion is introduced at the first chapter in this paper. Especially, the development, basic theories and assumptions on some major theories of seismic inversion are analyzed, discussed and summarized in mathematics and physics. Also, the problems faced by the mathematical basis of investigations of the seismic inversion are discussed, and inverse questions of strongly seismic scattering due to strong heterogeneous media in the Earth interior are analyzed and viewed. What the kernel of paper is that gathers all our attention making a new nonlinear inversion method of seismic scattering. The paper provides a theory and method of how to introduce the fixed-point theory into the nonlinear seismic scattering inversion and how to obtain the solution, and gives the actually method to create a serials of contractive mappings of velocity parameter's in the mapping space of wave. Therefore, the results testify the existence of fixed point of velocity parameter and give the method the find it. Further, the paper proves the conclusion that the value obtained by taking the fixed point of velocity parameter into wave equation is the fixed point of the wave of the contractive mapping. Thence, the fixed point is the global minima since the stabilities quality of the fixed point. Based on the new theory, in the chapter three, many inverse results are obtained in the numerical value test. By analysis the results one could find a basic facts that all the results, which are inversed by the different initial model, are tended to the true value in theoretical true model. In other words, the new method mostly eliminates the non-uniqueness that which is existed in seismic waves scattering nonlinear inversion in degree. But, since the test results are quite finite now, more test is need here to positive our theory. As a new theoretical method, it must be existed many weaken in it. The chapter four points out all the questions which is bother us. We hope more people to join us to solve the problem together.
Resumo:
These are two parts included in this report. In the first part, the zonation of the complexes in its series, lithofacies, the depth of magma source and chambers is discussed in detailed for the first time based on the new data of petrol-chemistry, isotopes, tectono-magma activity of Mesozoic volcano-plutonic complexes in the southern Great Hinggan Mts. Then, the genetic model of the zonality, double overlapped layer system, is proposed. The main conclusions are presented as follows: The Mesozoic volcanic-plutonic complexes in the southern Great Hinggan were formed by four stages of magma activity on the base of the subduction system formed in late Paleozoic. The Mesozoic magmatic activity began in Meso-Jurassic Epoch, flourished in late Jurassic Epoch, and declined in early Cretaceous Epoch. The complexes consist dominantly of acidic rocks with substantial intermediate rocks and a few mefic ones include the series of calc alkaline, high potassium calc alkaline, shoshonite, and a few alkaline. Most of those rocks are characterized by high potassium. The volcano-plutonic complexes is characterized by zonality, and can be divided mainly into there zones. The west zone, located in northwestern side of gneiss zone in Great Xinggan mountains, are dominated of high potassium basalts and basaltic andesite. The middle zone lies on the southeast side of the Proterozoic gneiss zone, and its southeast margin is along Huangganliang, Wushijiazi, and Baitazi. It composed of dominatly calc-alkaline, high potassium calc-alkaline rocks, deep granite and extrusive rhyolite. The east zone, occurring along Kesheketong Qi-Balinyou Qi-Balinzuo Qi, is dominated of shoshonite. In generally, southeastward from the Proterozoic gneiss zone, the Mesozoic plutons show the zones-mica granitites zone, hornblende-mica granitite zone, mica-hornblende granitite zone; the volcanic rocks also display the zones of calc alkaline-high potassium calc alkaline and shoshonites. In the same space, the late Paleozoic plutons also display the same zonality, which zones are combined of binary granite, granodiorite, quartz diorite and diorite southeast wards from the gneiss. Meso-Jurassic Epoch granite plutons almost distribute in the middle zone on the whole. Whereas late Jurassic Epoch volcanic rocks distribute in the west and east zone. This distribution of the volcano-plutonic complexes reveals that the middle zone was uplifted more intensively then the other zones in Meso-Jurassic and late Jurassic Epoches. Whole rock Rb-Sr isochron ages of the high potassium calc-alkaline volcanic rocks in the west zone, the calc-alkaline and high potassium calc-alkaline granite the middle zone, shoshonite in the east zone are 136Ma, 175Ma and 154Ma, respectively. The alkaline rocks close to the shoshonite zone is 143Ma and 126Ma. The isochron ages are comparable well with the K-Ar ages of the rocks obtained previously by other researchers. The compositions of Sr ans Nd isotopes suggest that the source of Mesozoic volcanic-plutonic complexes in Great Hinggan Mts. is mostly Paleo-Asia oceanic volcanic-sedimentary rocks, which probably was mixed by antiquated gneiss. The tectonic setting for Mesozoic magmatism was subductive continental margin. But this it was not directly formed by present west Pacific subduction. It actully was the re-working of the Paleozoic subduction system( which was formed during the Paleo-Asia ocean shortening) controlled by west Pacific subduction. For this reason, Although Great Hinggan Mts. is far away from west Pacific subduction zone, its volcanic arc still occurred echoing to the volcanic activities of east China, it, but the variation trend of potassium content in volcano-plutonic complexes of Great Hinggan is just reverse to ones of west Pacific. The primitive magmas occurred in the southern Great Hinggan Mts. Include high-potassium calc-alkaline basalt, high potassium calc-alkaline rhyolite, high potassium rhyolite, non-Eu negative anomaly trachy-rhyolite et al. Therefore, all of primitive magmas are either mafic or acid, and most of intermediate rocks occurring in the area are the products of Mesozoic acid magma contaminated by the Paleozoic volcanic- sedimentary rocks. The depth of those primitive magma sources and chambers gradually increase from northwest to southeast. This suggests that Paleozoic subduction still controlled the Mesozoic magmatism. In summary, the lithosphere tectonic system of the southern Great Hinggan Mts. controlling Mesozoic magmatism is a double overlapped layer system developing from Paleozoic subduction system. For this reason, the depth of crust of the southern Great Hinggan Mts. is thicker than that of its two sides, and consequently it causes regional negative gravity abnormity. The second part of this report shows the prolongation of the research work carried on in my doctor's period. Author presents new data about Rb-Sr and Sm-Nd isotopic compositions and ages, geochamical features, genesis mineralogy and ore deposit geology of the volcanic rocks in Kunyang rift. On the base of the substantial work, author presents a prospect of copper bearing magnetite ore deposit. The most important conclusions are as follows: 1. It is proved that all of these carbonatites controlled by a ringing structure system in Wuding-Lufeng basin in the central Yunnan were formed in the Mesoproterozoic period. Two stages could be identified as follows: in the first stage, carbonatitic volcanic rocks, such as lavas(Sm-Nd, 1685Ma), basaltic porphyrite dykes(Sm-Nd, 1645Ma), pyroclastic rocks and volcaniclastic sedimentary rocks, formed in the outer ring; in the second stage, carbonatitic breccias and dykes(Rb-Sr, 1048 Ma) did in the middle ring. The metamorphic age of the carbonatitic lavas (Rb-Sr, 893 Ma) in the outer ring was determined. The magma of carbonatitic volcanic rocks derived mainly form enriched mantle whose basement is depleted mantle that had been metasomated by mantle fluid and contaminated by Archaean lower crust. Carbonatitic spheres were discovered in ore bearing layers in Lishi copper mining in Yimen recently, which formed in calcite carbonatitic magma extrusion. This discovery indicates that the formation of copper ore deposit genesis relates to carbonatitic volcanic activity. The iron and copper ore deposits occurring in carbonatitic volcanic- sedimentary rocks in Kunyang rift results from carbonatitic magmatism. Author calls this kind of ore deposits as subaqueous carbonatitic iron-copper deposit. The magnetic anomaly area in the north of Lishi copper mining in Yimen was a depression more lower than its circumference. Iron and copper ores occurrig on the margin of the magnetic anomaly are volcanic hydrothermal deposit. The magnetic body causing the magnetic anomaly must be magnetite ore. Because the anomaly area is wide, it can be sure that there is a large insidious ore deposit embedding there.
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The content of this paper is based on the research work while the author took part in the key project of NSFC and the key project of Knowledge Innovation of CAS. The whole paper is expanded by introduction of the inevitable boundary problem during seismic migration and inversion. Boundary problem is a popular issue in seismic data processing. At the presence of artificial boundary, reflected wave which does not exist in reality comes to presence when the incident seismic wave arrives at the artificial boundary. That will interfere the propagation of seismic wave and cause alias information on the processed profile. Furthermore, the quality of the whole seismic profile will decrease and the subsequent work will fail.This paper has also made a review on the development of seismic migration, expatiated temporary seismic migration status and predicted the possible break through. Aiming at the absorbing boundary problem in migration, we have deduced the wide angle absorbing boundary condition and made a compare with the boundary effect of Toepiitz matrix fast approximate computation.During the process of fast approximate inversion computation of Toepiitz system, we have introduced the pre-conditioned conjugate gradient method employing co circulant extension to construct pre-conditioned matrix. Especially, employment of combined preconditioner will reduce the boundary effect during computation.Comparing the boundary problem in seismic migration with that in Toepiitz matrix inversion we find that the change of boundary condition will lead to the change of coefficient matrix eigenvalues and the change of coefficient matrix eigenvalues will cause boundary effect. In this paper, the author has made an qualitative analysis of the relationship between the coefficient matrix eigenvalues and the boundary effect. Quantitative analysis is worthy of further research.
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In recent years, global online shopping grows rapidly, China's growth rate is far greater than the average level of the world. Online shopping as a new type of shopping patterns gradually drew the researcher's attention. There were so many existing researches on the relationship between consumer characteristic and online shopping attitude and intention, but few togethered the different abstract levels of consumer characteristic in one research. In this study, 3M Model was introduced as theory guide of whole research work, the Chinese consumers who knew about the online shopping was the research object, questionnaire survey was used to collect the data, different abstract levels of consumer characteristic were togethered in a hierarchical model, tried to establish a model to explain the relationship between different abstract levels of consumer characteristic and online shopping attitude and intention. In addition, the study also compared the models posed by data from different consumer groups. The results showed that: First, consumers’ openness, need for arousal, assessment of online shopping experience, perceived risk of online shopping would affect their online shopping attitude and online shopping intention. Second, openness, need for arousal indirectly influenced the online shopping intention through the perceived risk of online shopping. Third, the perceived risk of online shopping indirectly influenced the online shopping intention through online shopping attitude. Fourth, assessment of online shopping experience indirectly influenced the online shopping intention through the perceived risk of online shopping and online shopping attitude. Fifth, only online shopping attitude would directly affect online shopping intention. It also worked as a mediator variable in the final model. Sixth, network age, risk propensity did not significantly affect the online shopping attitude and online shopping intention. Seventh, freight fluctuation can affect student more than in-service on online shopping intention.
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In the early part of this century, with the change from the seller's market to the buyer market, the competition between companies changed from product competition, selling competition to corporate image competition, and companies began to consciously build corporate reputation through fast developed mass media. As a result, a series of methods to build corporate image were created, such as advertising, public relations and corporate identify system(CIS), which ,in turn, promoted the development of the research of corporate image. The factors of corporate image have been the central issue of the corporate image research, for the probe of this issue is of great significance to both the development of corporate image theory and the practice of corporate image building. As far as the literature we have gathered is concerned, the exiting research on this topic either remains at the level of qualitative investigating and induction, or is limited in some particular industry. Therefore. There bean no commonly accepted corporate image theory so far. In the recent years, with the introduction of competition mechanism and the establishment of the company. As subject position in the market, the building of corporate image gas been developed quickly in our country, and the development of practice imperatively requires the guide of scientific theory. On the basis of the analysis and summarization of the research of the predecessors, the present dissertation attempts to do some investigation and research work on the common and individual characteristics of corporate image factors of the companies in different industries in our country. The method of questionnaire survey is used in the present research. The subject sample is gathered on the basis of convenience and feasibility, and at the mean time, some consideration is also given to straticulate randomization principles. The subjects are asked to select one of their most familiar companies, and determine the important of even item in the questionnaire to the selected company(i.e. the importance assessment), and then, determine the grades the selected company gains on every item(i.e. the image assessment). The discriminant analysis of corporate image of different industries. The selected sample is grouped and coded according to the standard of industry classification. The discriminant analysis is done with the selected companies as the sample and the grades of image assessment as the variables. The result indicates that industry variable is an important standard of the classification of corporate image, and the companies in the same industry are more similar in corporate image. The analysis of the common and individual characteristics of corporate image of different industries. Firstly, in every industry, the items are sieved according to the grades of importance assessment, and exploratory factor analysis is done with grades of image assessment on the selected items as the variables. Secondly, the factors drawn from every industry in arranged in order according to their importance. The result indicates that the corporate image of different industries shares some common characteristics, for there exist common factors among different industries. In the mean while, the corporate image of different industries has its individual characteristics, that is, there is some difference in the domain of the factors, and in the order of the factors(including the difference of the principle factor).